The long-range goal of this Program Project is to develop vaccine strategies against mucosal SIV (and HIV in the future) transmission, with a special focus on identifying local and systemic mechanisms leading to protecfive B cell development and antibody production. The objectives for the Primate Core are to provide the experimental animals and support services needed to facilitate the efficient completion of the aims outlined in Project 1, 2, 3 and 4. This will include the provision of retrovirus-free adult female rhesus macaques from the Yerkes rhesus macaque breeding colonies;immunizafions using the various immunizafion platforms (Projects 1 and 2) sample collections (for all projects) and repeated low dose vaginal challenges with SIVsmE660. The Primate Core tasks also include daily monitoring ofthe experimental animals;periodic physical examinafions with blood collecfions for immunologic and virologic evaluations and procurement/shipment of samples to the Program Project invesfigators;the performance of CBCs and laboratory analyses as needed;Perform euthanasia with sample collecfion and processing for Projects 3 and 4;and the performance of a basic gross and histologic necropsy evaluations of all experimental animals that die or are sacrificed during the course of this study. Provision of these resources and support services will facilitate the development and testing of novel AIDS vaccine concepts proposed in this Program Project. The Primate Core will play a key role in the development of a vaccine to prevent mucosal transmission and pathogenicity of SIV and HIV and the determination Of correlates of such protection. Vaccine efficacy will be evaluated by its ability to 1) prevent acquisition of infecfion (sterilizing immunity) or 2) significant control of viremia post-challenge and preservation of protective immune responses.